While Elon Musk was claiming that Tesla Motors will produce 500,000 electric cars in 2018 and 1,000,000 cars in 2020, a leading short-seller on Wall Street admitted he is now betting heavily against Tesla.

Tesla Motors Inc. caused a sensation by picking up $300 million in Model 3 customer deposit cash in just 96 hours this week. The hidden story: that money may have rescued Tesla from a precarious negative working capital crisis. Tesla now has the opportunity to become a profitable car company for the first time.

The glamour of the Tesla Model 3 premier this week created a huge surge in orders, but with commodity lithium prices used in Tesla batteries spiking 20 percent and expected to jump another 20 percent, inflationary costs may ruin Tesla’s electric car business.

When Tesla Motors Inc. CEO Elon Musk unveiled a line of home and commercial battery packs a week ago, he said Tesla was “trying to change the fundamental energy infrastructure of the world.” Although the system Musk announced was better than the competition, the cost was assumed to be too expensive except for home solar systems. But now it turns out that Tesla’s new batteries do not even make economic sense to back-up rooftop solar systems–at least not yet.